Short, straight, mostly oblique to the midrib. Indusium rather narrow,
opening toward the midrib, fronds lobed or variously divided. Spleenworts.
_Asplenium_.

[Illustration]

Short, indusium usually more or less curved and frequently crossing a vein.
The large spleenworts including Lady Fern. _Athyrium_.




DESCRIPTIVE TEXT OF THE FERNS


In this manual our native ferns are grouped scientifically under five
distinct families. By far the largest of these groups, and the first to be
treated, is that of the _real ferns (Polypodiàceæ)_ with sixty species and
several chief varieties. Then follow the _flowering ferns (Osmundàceæ)_
with three species; the _curly grass_ and _climbing ferns (Schizæàceæ)_
with two species; the _adder's tongue_ and _grape ferns (Ophioglossàceæ)_
with seven species; and the _filmy ferns (Hymenophyllàceæ)_ with one
species.

Corresponding with these five families, the sporangia or spore cases of
ferns have five quite distinct forms on which the families are founded.

[Illustration: Fig. 1]